package org.bouncycastle.asn1.x509;

import java.io.IOException;
import java.util.Enumeration;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERBitString;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;

/**
 * The object that contains the public key stored in a certficate.
 * <p>
 * The getEncoded() method in the public keys in the JCE produces a DER encoded
 * one of these.
 */
public class SubjectPublicKeyInfo extends ASN1Encodable {
    private AlgorithmIdentifier algId;
    private DERBitString keyData;

    public static SubjectPublicKeyInfo getInstance(ASN1TaggedObject obj,
            boolean explicit) {
        return getInstance(ASN1Sequence.getInstance(obj, explicit));
    }

    public static SubjectPublicKeyInfo getInstance(Object obj) {
        if (obj instanceof SubjectPublicKeyInfo) {
            return (SubjectPublicKeyInfo) obj;
        } else if (obj != null) {
            return new SubjectPublicKeyInfo(ASN1Sequence.getInstance(obj));
        }

        return null;
    }

    public SubjectPublicKeyInfo(AlgorithmIdentifier algId,
            DEREncodable publicKey) {
        this.keyData = new DERBitString(publicKey);
        this.algId = algId;
    }

    public SubjectPublicKeyInfo(AlgorithmIdentifier algId, byte[] publicKey) {
        this.keyData = new DERBitString(publicKey);
        this.algId = algId;
    }

    @SuppressWarnings("rawtypes")
    public SubjectPublicKeyInfo(ASN1Sequence seq) {
        if (seq.size() != 2) {
            throw new IllegalArgumentException("Bad sequence size: "
                    + seq.size());
        }

        Enumeration e = seq.getObjects();

        this.algId = AlgorithmIdentifier.getInstance(e.nextElement());
        this.keyData = DERBitString.getInstance(e.nextElement());
    }

    public AlgorithmIdentifier getAlgorithmId() {
        return algId;
    }

    /**
     * for when the public key is an encoded object - if the bitstring can't be
     * decoded this routine throws an IOException.
     * 
     * @exception IOException
     *                - if the bit string doesn't represent a DER encoded
     *                object.
     */
    public DERObject getPublicKey() throws IOException {
        ASN1InputStream aIn = new ASN1InputStream(keyData.getBytes());

        return aIn.readObject();
    }

    /**
     * for when the public key is raw bits...
     */
    public DERBitString getPublicKeyData() {
        return keyData;
    }

    /**
     * Produce an object suitable for an ASN1OutputStream.
     * 
     * <pre>
     * SubjectPublicKeyInfo ::= SEQUENCE {
     *                          algorithm AlgorithmIdentifier,
     *                          publicKey BIT STRING }
     * </pre>
     */
    public DERObject toASN1Object() {
        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(algId);
        v.add(keyData);

        return new DERSequence(v);
    }
}
